The subject of the present invention is a metal diaphragm for a diaphragm-type valve.
In known fashion, a diaphragm-type valve has a body in which are provided fluid inlet and discharge channels, whereby the inlet channel terminates in a face opposite which the diaphragm is mounted. The diaphragm, by deformation, is able to isolate or place in communication the fluid inlet and discharge channels by blocking or unblocking the end of the fluid inlet channel which forms a seat for the diaphragm.
It is useful to employ diaphragm-type valves when excellent sealing properties as well as elimination of contamination of the fluid transported are desired, particularly by minimizing the microparticles that might detach from the components of the valve, and when the goal is to minimize gap zones that are incompatible with the use of pure fluid, in view of the small-volume cavities that these zones delimit, where particles may accumulate, and where they may detach at any moment in time. Moreover, in these gap zones, quantities, even small quantities, of residual fluid may remain, which cannot be eliminated by flushing. If these fluids have aggressive chemical properties, these retention zones increase the likelihood of corrosion.
A diaphragm-type valve has, by comparison with a bellows-type valve, the advantage of limiting the gap zones, and avoiding losses of microparticles of material. Also, the diaphragm must not be associated with an actuating element such as a spring located in the fluid channel, as this is also likely to release damaging particles.
A first solution consists of using a plane diaphragm. Such a diaphragm type is not entirely satisfactory since the travel between the closed position and the open position of the valve is short, so that the flow coefficient is also limited. Moreover, in the peripheral zone in which the diaphragm is attached to the base of the valve, the material creeps, resulting in leaks at the point of attachment.
One solution which initially would appear to be attractive consists of using a corrugated diaphragm which allows the flexibility as well as the travel of the diaphragm to be increased. However, experience shows that the corrugations in the diaphragm stiffen it, and leave dead spaces inside the corrugations which form fluid retention zones.